High‐temperature oxidation of Ti3Al0.7Si0.3C2compound at 900 and 1000 °C in air

Abstract

The compound, Ti3Al0.7Si0.3C2, was synthesized by hot pressing a powder mixture of TiCX (x = 0.6), Al and Si. Its oxidation at 900 and 1000 °C in air for up to 50 h resulted in the formation of rutile-TiO2, α-Al2O3 and amorphous SiO2. The oxide scales formed consisted of triple layers, viz, an outer TiO2 layer containing Al2O3 particles, an intermediate Al2O3 layer, and an inner mixed layer that was rich in TiO2, but deficient in Al2O3 and SiO2. During oxidation, Ti diffused outwards to form the outer TiO2 layer, and oxygen was transported inwards to form the inner mixed layer. At the same time, carbon was liberated from Ti3Al0.7Si0.3C2. Ti3Al0.7Si0.3C2 oxidized slower than the TiO2-forming kinetics, but faster than the (α-Al2O3 or SiO2)-forming kinetics.